Device for adjusting the armature stroke of a solenoid valve

ABSTRACT

A device for adjusting an armature stroke of an armature upon actuation of a magnet of an electromagnetic valve having a stop bush disposed in an axial guide relative to a main body of the electromagnetic valve and adjustable in its axial position relative to the main body of the electromagnetic valve, which stop bush forms a stop for limiting the armature stroke in an axial direction. A variable adjusting element with two threaded portions providing a variable thread pitch (P) and the same thread direction by which the position of the stop bush is adjustable. The first threaded portion engages a corresponding first threaded portion of the stop bush, and the second threaded portion engages a corresponding second threaded portion of the main body, and to an electromagnetic valve having a corresponding device, in particular for use in a fuel injector.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 USC 371 application of PCT/DE 03/02128 filed onJun. 26, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

For supplying fuel to combustion chambers of internal combustionengines, injection systems for injecting fuel are used whose injectorsare exposed to extremely high pressures. In order not to impair theefficiency of such fuel injectors, it is absolutely necessary to assurereplicable injector performance. Suitable injectors as a rule have anelectromagnetic valve, and an armature stroke of such an electromagneticvalve must be adjusted precisely when applicable injectors are beinginstalled, since the injector dynamics are definitively affected by thearmature stroke. For instance, given a fixed triggering duration of amagnet coil of the electromagnetic valve, the injected fuel quantity isdependent on the armature stroke.

2. Description of the Prior Art

In currently known electromagnetic valves used in conjunction withinjectors in injection systems for fuel supply purposes, the armaturestroke is adjusted via adjusting rings, which fix the axial position ofa corresponding armature stop. Via the armature, or the motion of thearmature in the axial direction and its axial (terminal) position, theopening of a nozzle of the injector and thus the injected fuel quantityare defined. When an electromagnetic valve or an injector is assembled,the components that determine the armature stroke are measured, and onthe basis of the measurement results, the dimensions, required for acertain predetermined armature stroke, of a adjusting ring are attained.A magnet group, together with the adjusting ring dimensioned inaccordance with the calculation, is then screwed to the injector body,and then the armature stroke is measured in the screwed-together or inother words tightened state. For use in extremely high-pressureinjection system injectors, however, acceptable tolerances for thearmature stroke are in the micrometer range, if replicable injectorperformance is to be assured. Because of the only slight deviations intolerances allowed, after an initial installation as described above thearmature stroke does not always remain within the tolerance values. Toassure the adjusting of the armature stroke within the close tolerancevalues then, the magnet group must be completely removed, and thearmature stroke must be reset by way of the choice of an adjusting ringof a different size. Possibly this operation may even have to berepeated more than once, until acceptable adherence to tolerances of thearmature stroke can be attained. This process leads to high costs inproduction.

In view of the stringent requirements for accuracy in adjusting thearmature stroke of electromagnetic valves, especially for used inconjunction with injectors in injection systems for injecting fuel intocombustion chambers of internal combustion engines, it is desirable andnecessary to assure the accuracy of the adjustment of the armaturestroke without additional installation requirements.

The present invention has the object in particular of furnishing adevice for adjusting an armature stroke of an armature of anelectromagnetic valve, in particular for use in conjunction withinjectors in injection systems, by which even after an initialinstallation, because it is possible to adjust the armature stroke,dismantling again if the armature stroke is adjusted incorrectly isunnecessary, and as a result the production costs can be reduced. Animproved tolerance position of the armature stroke moreover makes amore-precise output of a fuel quantity from a suitably equippedinjector.

SUMMARY OF THE INVENTION

The embodiment according to the invention of a device for adjusting anarmature stroke of an electromagnetic valve advantageously enablesadjusting of the armature stroke even from outside after an initialinstallation, and as a result, if an armature stroke is outside thetolerance values, there is no need for an incorrectly adjustedelectromagnetic valve to be dismantled. According to the invention, itis possible for an armature stroke, which follows actuation of a magnetof the electromagnetic valve, to be adjusted via a variable adjustingelement which has two threaded portions of differing thread pitch (P)and which is still attainable and adjustable even after theelectromagnetic valve and/or an entire injector which has theelectromagnetic valve has been assembled. The thread direction of thetwo threaded portions is the same. By way of the adjustment of theadjusting element, the position of a stop bush which is disposed in anaxial guide is adjustable and the stop bush is adjustable in its axialposition with respect to a main body of the electromagnetic valve. As aresult of its axial position as adjusted, the stop bush forms a stop forthe armature to limit the armature stroke in an axial direction of theelectromagnetic valve. The adjustment in the axial position of the stopbush relative to the main body of the electromagnetic valve via theadjusting element is effected in such a way that a first threadedportion of the adjusting element engages a corresponding first threadedportion of the stop bush with the same thread pitch, and that a secondthreaded portion of the adjusting element engages a corresponding secondthreaded portion of the main body with the same thread pitch. Therespective thread pitches of the respective first and second threadedportions differ; that is, the thread pitch of the respective firstthreaded portions is for instance less than the thread pitch of therespective second threaded portions. Effectively, upon appropriateadjustment of the adjusting element, the result is an axial adjustmentof the position of the stop bush relative to the main body, and this isthe result of the difference between the two different thread pitches.It should be noted that the respective threaded portions of theadjusting element may have female or male threads, which then engagecorresponding male- or female-threaded portions in the stop bush or themain body. As long as all the corresponding threads each have the samethread direction, in principle any combination of female- andmale-threaded portions is possible. Also, the first threaded portion ofthe stop bush may be cut directly into the stop bush, but it is alsopossible for a special element of the stop bush optionally to have thecorresponding first threaded portion of the stop bush. The same is truefor the second threaded portion of the main body; there as well it ispossible for the second threaded portion to be cut directly into themain body, but it is also possible for the second threaded portion ofthe main body to be disposed in an element especially intended for itthat is part of the main body. The two threaded portions of theadjusting element may also be cut directly into the adjusting element,but it is also possible to provide additional special elements of theadjusting element here that each have the respective threaded portions.In general, such special elements may for instance be cuffs, bushes, orthe like.

In an advantageous feature of the invention, the magnet or magnetassembly, which may comprise an electromagnet assembly with coils, maybe disposed essentially around the stop bush, but it is also possiblefor the magnet or corresponding magnet assembly to be disposedessentially in the stop bush. “Essentially” should be understood here tomean that the magnet does not entirely surround the corresponding stopbush, or that the corresponding magnet is not entirely surrounded by thestop bush. By this kind of disposition of the magnets and stop bush, onthe one hand especially good accessibility to the stop bush exists,depending on given conditions, and on the other, a space-saving designof the device or electromagnetic valve of the invention that suits themost various installation conditions can be attained, which in turn canlead to savings of material and thus to a reduction in production costs.

The axial guide of the stop bush, in preferred embodiments of theinvention, may be disposed in the magnet, but it is also possible forthe axial guide of the stop bush to be disposed in the main body.Depending on the given installation situation, efficient and reliableaxial guidance of the stop bush is possible, which serves the purpose ofaccuracy and reliability of the adjustment of the armature stroke.

In a preferred embodiment of the invention, the axial guide may beformed by at least one recess, in which a corresponding protrusion ofthe stop bush is guided. This recess may, as described above, bedisposed either in the magnet or in the main body. It is also possiblefor the corresponding recess to be embodied in additional specialelements, such as cuffs, bushes or the like, of either the magnet or themain body. Preferably, at least two recesses and correspondingprotrusions are provided; however, it is also possible for only onerecess and a corresponding protrusion, or three or more recesses eachwith corresponding protrusions, to be provided. The recess or recessesextend in the axial direction at least as far as is required for theadjustability of the armature stroke. Specifically when the device ofthe invention is used in electromagnetic valves in injectors inhigh-pressure injection systems, especially secure axial guidance of thestop bush, making reliable adjustment of the armature stroke possible,is attainable because of the preferred design according to theinvention.

In a further preferred embodiment, the axial guide may also be formed byat least one flattened region, on which a correspondingly flattenedregion of the stop bush is guided. Once again, a plurality of suchregions may be embodied, but preferably two such regions are embodied.The flattened region or regions extend in the axial direction at leastas far as the adjustability of the armature stroke requires. It is alsopossible for the flattened regions to be embodied in additional specialelements, such as cuffs, bushes or the like, of either the magnet or themain body. This further preferred design according to the invention ofthe axial guide permits an optionally somewhat simpler design of theregion of the axial guide, and as a result production costs can bereduced still further.

In electromagnetic valves, it is moreover necessary for the so-calledremanent air gap, that is, the spacing between the armature and themagnet or magnet assembly, also to be adjusted upon actuation of theelectromagnetic valve. According to the invention, this canadvantageously be accomplished by providing a remanent air gap adjustingdisk which by its thickness determines the remanent air gap between themagnet or magnet assembly and the armature, when the armature rests onthe stop bush and reaches its corresponding terminal stroke position.For example, the remanent air gap adjusting disk may be disposed in aregion between a corresponding receptacle on the stop bush and themagnet. Advantageously, a defined value for the size of the remanent airgap can thus already be predetermined upon initial installation.

An embodiment of the present invention in which the stop bush is formedby a magnet bush itself is especially preferred. The stop bush embodiedas a magnet bush then surrounds the magnet or magnet assemblycompletely, making it possible to reduce the number of components, sincethe corresponding magnet bush simultaneously acts as a stop bush aswell.

The same advantage of cost reduction for a simultaneously use-specificcomponent design is offered by a preferred embodiment of the presentinvention in which the adjusting element is formed by a magnet clampingnut, which screws a magnet bush, which may for instance also be embodiedas a stop bush, to the main body, which for example may also be formedby an injector body directly.

To enable an especially fine adjustment of the armature stroke, thevalue of the difference between the various pitches of the two threadedportions is preferably in a range from 0.02 to 0.10, and especiallypreferably at a value of 0.05. In other words, the thread pitch of therespective first threaded portions, for instance, is P₁=0.70 mm, and thethread pitch of the respective second threaded portions is P₂=0.75 mm.The difference between the thread pitches is 0.05. Over a complete 360°rotation of the adjusting element, the axial position of the stop bushthus changes relative to the main body by 0.05 mm.

The electromagnetic valve of the invention having the characteristics ofclaim 10, which is intended in particular for use in a fuel injector,has a magnet or magnet assembly and an armature, and also has a devicefor adjusting an armature stroke of the armature upon actuation of themagnet, having a stop bush is disposed relative to a main body of theelectromagnetic valve or of the injector in an axial guide and isadjustable in its axial position relative to the main body, wherein thisstop bush forms a stop for limiting the armature stroke in an axialdirection, and wherein the device for adjusting the armature stroke hasan variable adjusting element with two threaded portions of differentthread pitch (P) and the same thread direction, by which element theposition of the stop bush is adjustable, and the first threaded portionengages a corresponding first threaded portion of the stop bush, and thesecond threaded portion engages a corresponding second threaded portionof the main body. Because of the adjustability—even retroactively—of theaxial position of the stop bush by a suitable adjusting element,economical production of a corresponding electromagnetic valve ispossible, and in particular in the use of an electromagnetic valve ofthis kind, because of the resultant possibility of close-tolerancearmature stroke adjustment, replicable injector performance is assured.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in further detail below in conjunction withthe drawings, in which:

Shown are:

FIG. 1 a is a schematic illustration of an adjusting device thatexplains the fundamental principle of the present invention;

FIG. 1 b is a sectional view of the schematic illustration of FIG. 1 ataken along the line lb;

FIG. 2 is a first preferred embodiment of an electromagnetic valvehaving a device according to the invention for adjusting an armaturestroke;

FIG. 3 a is a fragmentary section through a second preferred embodimentof an electromagnetic valve, with adjustment of an armature stroke inaccordance with the present invention;

FIG. 3 b is a detail of a further variant of the embodiment of thepresent invention shown in FIG. 3 a;

FIG. 4 a is an electromagnetic valve having a device for adjusting anarmature stroke in a further preferred embodiment of the presentinvention; and

FIG. 4 b is a cross-sectional view of a stop bush of the embodiment ofthe invention shown in FIG. 4 a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1, in a fragmentary sectional view, is a schematic illustration ofthe device according to the invention for adjusting an armature strokeof an armature of an electromagnetic valve.

In a main body 2, which is part of an electromagnetic valve 1, a stopbush 4 is disposed in such a way that by means of an axial guide 10 itis guided movably in the main body 2. The axial guide 10 is formed bytwo recesses 12 in the main body 2 and two corresponding protrusions 13of the stop bush 4 which are received in these recesses. The stop bush4, in an inner region thereof, has a first threaded portion 8 which isdesigned as a female thread. The main body 2, in its upper portion, hasa second threaded portion 9 which is embodied as a female thread. Anadjusting element 5 is disposed in both the main body 2 and stop bush 4and rotatably engages these elements with a first threaded portion 6 anda second threaded portion 7, respectively, in the respective firstthreaded portion 8 of the stop bush 4 and the second threaded portion 9of the main body 2 and meshes with each of these as applicable. Thevarious threaded portions have different pitches; the first threadedportions 6, 8 in this example have a pitch of P₁=0.70mm, for instance,and the second threaded portions 7, 9 each have a thread pitch ofP₂=0.75 mm. If as represented by the arrow in FIG. 1 a the adjustingelement 5 is now rotated counter to the fixed main body 2 and counter tothe stop bush 4, which is prevented via the axial guide from rotatingcounter to the fixed main body 2, the result is an axial displacement ofthe stop bush 4 relative to the main body 2. In the example selected,the axial displacement of the stop bush 4 relative to the main body 2upon one rotation of the adjusting element 5 would beP₂−P₁=0.75−0.70=0.05, or in other words 0.05 mm of axial displacement.The stop bush 4 acting as a stop for limiting the armature stroke of anarmature (not shown) would thus vary the armature stroke by 0.05 mm uponone rotation of the adjusting element 5. The precise adjustment of thearmature stroke can be effected via the variable adjusting element 5even after assembly has been done.

FIG. 1 b shows a fragmentary sectional view of the axial guide 10 of thestop bush 4 in the main body 2, taken along the section line lb of FIG.1 a.

The stop bush 4 is secured against rotating relative to the main body 2by the axial guide 10. In the embodiment of FIGS. 1 a and 1 b, thiseffected by providing that the axial guide 10 is formed by two recesses12 in the main body 2, in each of which recesses a correspondingprotrusion 13 of the stop bush 4 is guided.

FIG. 2 shows a first preferred embodiment of the device for adjusting anarmature stroke, as it is used in an electromagnetic valve 1.

A stop bush 4 is disposed axially movably in an axial guide 10 in themain body 2 of the electromagnetic valve 1; in its embodiment, the axialguide 10 is essentially equivalent to the disposition of an axial guide10 shown in FIGS. 1 a and 1 b. An adjusting element 5 is introduced frombelow into the main body 2 and the stop bush 4, and respective firstthreaded portions 6 and 8 in a region of the stop bush 4 and secondthreaded portions 7 and 9 in a region of the main body 2 respectivelyengage one another. By rotation of the adjusting element 5 at anadjusting portion 19, it is thus possible, via the first and secondthreaded portions, which have different pitches but the same threadcourse direction, to make an axial change in the position of the stopbush 4 in the main body 2; as soon as the correct position has beenestablished, the corresponding position of the adjusting element 5 canbe fixed via a lock nut 20. A magnet 11, designed as an electromagnet,of the electromagnetic valve 1 is disposed around the stop bush 4, in alower region of this stop bush 4. Via a magnet bush 17 of theelectromagnetic valve 1, the magnet 11 is sealed off from theenvironment. Between the magnet 11 and a stop, provided appropriatelyfor it, of the stop bush 4, there is a remanent air gap adjusting disk16, in the embodiment of FIG. 2, which upon actuation of theelectromagnetic valve 1 (this situation is shown in FIG. 2) defines thethickness of the remanent air gap between the corresponding underside ofthe magnet 11 and the top side of the armature 3. Upon actuation of theelectromagnetic valve, the armature is pulled upward far enough that islimited in its stroke by striking against the corresponding stop of thestop bush 4. However, at that time it does not yet rest on the magnet11, which is disposed around the corresponding stop region of the stopbush 4; instead, there is still a remanent air gap remaining between themagnet 11 and the armature 3, whose size is adjustable via the thicknessof the remanent air gap adjusting disk 16, or in other words via theaxial position of the magnet relative to the stop of the stop bush. Itis possible, via an oil outlet bore 18, to measure the oil throughput,which is characteristic for the magnitude of the armature stroke, andthen optionally to adjust the armature stroke via a rotation of theadjusting element 5 by corresponding axial displacement of the stop bush4. By means of an armature spring (not shown here), all the moving partsof the adjusting mechanism are prestressed; in the case in which themagnet 11, which in the embodiment shown is designed as anelectromagnet, is subjected to current, or in other words pulls thearmature upward with a certain force, all the moving parts of theadjusting mechanism are prestressed upward, since otherwise they wouldbe incited to vibrate counter to the rotation of the armature 3. Thisprestressing and the components for it are not shown in FIG. 2. By wayof example, the prestressing could be brought to bear by a suitablydisposed wave spring washer below a core of the magnet; the force of thespring prestressing should be much greater than the force of the magnet.

In the exemplary embodiment of FIG. 2, the magnet 11 moves along withthe stop bush 4 in the event of a change in the axial position of thestop bush, so that upon a suitable adjustment of the armature stroke,the remanent air gap remains unchanged.

FIG. 3 a shows a second preferred embodiment of the device for adjustingan armature stroke of an electromagnetic valve; here, the stop bush 4 isformed by the magnet bush 17, which is completely surrounded by themagnet 11 (the magnet itself is located inside the magnet bush 17 and isnot shown), and the adjusting element 5 is embodied as a magnet clampingnut 21, which with its first threaded portion 6, embodied as a femalethread, engages the first threaded portion 8, correspondingly embodiedas a male thread, of the stop bush 4 and, with its second threadedportion 7, embodied as a female thread, engages the corresponding secondthreaded portion 9, embodied as a male thread, of the main body 2. Themain body 2 directly forms the actual injector body. The armature (notshown) is guided in an armature guide 22. Rotating the magnet clampingnut 21 embodied as an adjusting element 5 brings about an adjustment inthe axial position of the magnet bush 17, embodied as a stop bush 4,relative to the main body 2 embodied as an injector body. The magnettravels the same axial distance, together with the magnet bush 17. Toassure the installation of the device for adjusting the armature strokein accordance with the embodiment shown in FIG. 3 a, the region abovethe first threaded portion 8 of the magnet bush 17 must affordsufficient space, or in other words it must have approximately the sameheight as the total threaded portion. The magnet clamping nut 21, forinstallation, is rotated in advance to beyond the first threaded portion8 of the magnet bush 17; the magnet is pressed into the magnet bush 17;and then the magnet clamping nut 21 is also screwed to the main body 2.The stop bush 4 or magnet bush 17 that forms the stop bush 4 must besufficiently deformable, or else an elastic component must be built in,in this case in FIG. 3 a a wave spring washer 23, so that this washercan be deformed or prestressed upon suitable adjustment of the armaturestroke. Once the armature stroke has been adjusted, the magnet clampingnut 21 is secured against coming loose by a lock nut (not shown).

FIG. 3 b shows a deformation portion 24 of the magnet bush 17, designedas a stop bush 4, of the kind otherwise shown in the same way in FIG. 3a. Upon adjustment of the armature stroke, the deformation portion 24can be deformed appropriately as needed, as a result of which thearmature stroke is defined.

FIG. 4 a shows an embodiment of a device for adjusting the armaturestroke of an electromagnetic valve 1 of the kind used particularly incommon rail injectors, in which markedly greater tolerances for thevalues of the size of the remanent air gap are acceptable than is thecase for the values for the armature stroke. Thus if a device foradjusting an armature stroke is used in electromagnetic valves of commonrail injectors, an adjustment of the remanent air gap value is tolerableonce a fine adjustment of the armature stroke has been made. This makesa simplified embodiment of the device of the invention for adjusting anarmature stroke possible, compared to the embodiment of FIG. 2 a. Inthis simpler embodiment, the stop bush 4 has at least one flattenedregion 15 as its axial guide 10, and this flattened region is guided ona corresponding flattened region 14. In the case of the embodiment ofFIG. 4 a, the flattened region 14 is embodied on the magnet 11, which isfixed against rotation relative to the main body 2, but in principle itwould also be possible for this flattened region 14 to be provideddirectly on the main body 2, for instance. In the exemplary embodimentof FIG. 4 a, two flattened regions 14 and two corresponding flattenedregion 15 of the stop bush 4 are provided.

The magnet 11 is surrounded by a magnet bush 17, which seals it off fromthe environment. For assembly of a corresponding electromagnetic valve1, the adjusting element 5 is screwed into the stop bush 4, and then theunit thus formed is introduced into the surrounding magnet 11; theadjustment in the height of the region of the stop bush 4 that protrudespast the bottom plane of the magnet 11, which height in the insertedstate defines the remanent air gap, is effected by means of suitablyextensive screwing in of the first threaded portion 6 of the adjustingelement 5 into the first threaded portion 8 of the stop bush 4. Acertain reserve value is taken into account here. The adjusting element5 is screwed into the main body 2, or into the region of the outlet neckof this main body 2, by means of the adjusting portion 19 of theadjusting element 5, which portion is designed as a hexagonal socket.Because of the different thread pitch, it is then possible, as alreadyknown, to make an adjustment in the axial position of the stop bush 4relative to the main body 2, and as a result, since the magnet 11 andthe stop bush 4 in this embodiment are axially displaceable counter toone another, a corresponding fine adjustment of the remanent air gap issimultaneously possible. The armature stroke itself can then be adjustedin the known way via a suitable adjusting portion. This adjustingportion is not shown here in FIG. 4 a. Once the entire installation ofthe electromagnetic valve of the invention has thus been completed, afine adjustment of the armature stroke can then be made from above, viathe adjusting portion 19, embodied as a hexagonal socket, of theadjusting element 5, but in this process, because of the axialdisplaceability of the magnet 11 and stop bush, the size of the remanentair gap also varies. However, because of the aforementioned greatertolerance values for the remanent air gap, this is acceptable. The exactadjustment of the armature stroke can finally be fixed with the lock nut20. By means of a spring 25 with a suitably high spring rate, the threadplay in the stop bush 4 is overpressed. By a suitable design of thespring rate of the spring 25, damping of the activation recoil uponactuation of the electromagnetic valve 1 can be accomplished, and as aresult the performance graph curve data of the common rail injectorequipped with such an electromagnetic valve 1 can be varied.

FIG. 4 b in detail shows a plan view of the design of the stop bush 4 inthe embodiment of FIG. 4 a, in the region of the axial guide 10; inparticular, the two flattened regions 15 that are present in theexemplary embodiment can be seen.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

LIST OF REFERENCE NUMERALS

-   1 Electromagnetic valve-   2 Main body-   3 Armature-   4 Stop bush-   5 Adjusting element-   6 First threaded portion-   7 Second threaded portion-   8 First threaded portion of the stop bush-   9 Second threaded portion of the main body-   10 Axial guide-   11 Magnet-   12 Recess-   13 Protrusion-   14 Flattened region-   15 Flattened region of the stop bush-   16 Remanent air gap adjusting disk-   17 Magnet bush-   18 Oil outlet bore-   19 Adjusting portion-   20 Lock nut-   21 Magnet clamping nut-   22 Armature guide-   23 Wave washer-   24 Deformation portion-   25 Spring-   P Thread pitch-   P₁ Thread pitch of the first threaded portions-   P₂ Thread pitch of the second threaded portions

1. A device for adjusting an armature stroke of an armature (3) uponactuation of a magnet (11) of an electromagnetic valve (1), the devicecomprising a stop bush (4) disposed in an axial guide (10) relative to amain body (2) of the electromagnetic valve (1) and being adjustable inits axial position relative to the main body (2) of the electromagneticvalve, the stop bush forming a stop for limiting the armature stroke inan axial direction, a variable adjusting element (5) for adjusting theposition of the stop bush (2), the adjusting element (5) having twothreaded portions (6, 7) providing a variable thread pitch (P) and thesame thread direction, and a first threaded portion (8) on the stop bush(4) and a second threaded portion (9) on the main body (2), the firstthreaded portion (6) engaging and corresponding to the first threadedportion (8), and the second threaded portion (7) engaging andcorresponding to the second threaded portion (9).
 2. The device of claim1, wherein the magnet (11) of the electromagnetic valve (1) is disposedessentially around the stop bush (4).
 3. The device of claim 1, whereinthe magnet (11) of the electromagnetic valve (1) is disposed essentiallyin the stop bush (4).
 4. The device of claim 1, wherein the axial guide(10) is disposed in the magnet (11).
 5. The device of claim 2, whereinthe axial guide (10) is disposed in the magnet (11).
 6. The device ofclaim 3, wherein the axial guide (10) is disposed in the magnet (11). 7.The device of claim 1, wherein the axial guide (10) is disposed in themain body (2).
 8. The device of claim 2, wherein the axial guide (10) isdisposed in the main body (2).
 9. The device of claim 3, wherein theaxial guide (10) is disposed in the main body (2).
 10. The device ofclaim 1, wherein the axial guide (10) is formed by at least one recess(12), in which a corresponding protrusion (13) of the stop bush (4) isguided.
 11. The device of claim 2, wherein the axial guide (10) isformed by at least one recess (12), in which a corresponding protrusion(13) of the stop bush (4) is guided.
 12. The device of claim 3, whereinthe axial guide (10) is formed by at least one recess (12), in which acorresponding protrusion (13) of the stop bush (4) is guided.
 13. Thedevice of claim 1, wherein the axial guide (10) is formed by at leastone flattened region (14), on which a correspondingly flattened region(15) of the stop bush (4) is guided.
 14. The device of claim 2, whereinthe axial guide (10) is formed by at least one flattened region (14), onwhich a correspondingly flattened region (15) of the stop bush (4) isguided.
 15. The device of claim 1, further comprising a remanent air gapadjusting disk (16), which by its thickness determines the remanent airgap between the magnet (11) and the armature (4).
 16. The device ofclaim 3, wherein the stop bush (4) a magnet bush (17).
 17. The device ofclaim 3, wherein the adjusting element (5) is a magnet clamping nut(21).
 18. The device of claim 1, wherein the difference between thepitches (P) of the two threaded portions (6, 7) is in the range from0.02 to 0.10, and preferably is at a value of 0.05.
 19. Anelectromagnetic valve (1) for use in a fuel injector, which has a magnet(11) and an armature (3), further having an adjusting for adjusting anarmature stroke of the armature (3) upon actuation of a magnet (11) ofan electromagnetic valve (1), the adjusting device comprising a stopbush (4), disposed in an axial guide (10) relative to a main body (2) ofthe electromagnetic valve (1) and adjustable in its axial positionrelative to the main body (2) of the electromagnetic valve, which stopbush forms a stop for limiting the armature stroke in an axialdirection, wherein an variable adjusting element (5) with two threadedportions (6, 7), a variable thread pitch (P) and the same threaddirection on the adjusting element (5) by which the position of the stopbush (4) is adjustable; and wherein the first threaded portion (6)engages a corresponding first threaded portion (8) of the stop bush (4),and the second threaded portion (7) engages a corresponding secondthreaded portion (9) of the main body (2).